The invention is an improvement in a rigid jaw car coupler which is manufactured and sold by the foundry group of the Midland-Ross Corporation of Cleveland, Ohio, under the trademark WILLISON. This coupler is primarily used on mine cars and other similar industrial applications. Rigid jaw couplers of this type utilize a locklifting lever which extends exteriorly of the coupler for operating the locking mechanism to cause disengagement of a pair of interlocked couplers. The rigid jaw couplers, unlike knuckle type couplers, do not employ a mechanism for placing the lock in a lockset position, whereby a pair of interlocked couplers can be readily disengaged. At present, an operator must be physically present to maintain the lock of at least one of a pair of interlocked rigid jaw couplers in an open position during the uncoupling operation and, if necessary, even go between a pair of coupled mine cars to operate the levers used in controlling the position of the locks for uncoupling.
U.S. Pat. No. 2,951,597 is directed to a locksetting mechanism for placing the lock of a rigid jaw coupler in a lockset position to permit subsequent disengagement of a pair of interlocked couplers. The operation of this mechanism is reliant on the use of a specially designed pawl which cooperates with the locklifting lever to hold the lock in a lockset position until the interlocked couplers are separated, after which the lock returns from lockset to a locked position. The pawl does not function as smoothly as it should, because of the frictional forces generated by the pawl as it slides up and down an inclined surface which is disposed in the bottom of the coupler head and used to cause lifting of the pawl out of interlocking engagement with the locklifting lever, as the lock moves from lockset to a locked position.
Copending Patent Application Ser. No. 916,475, filed June 19, 1978, and now U.S. Pat. No. 4,203,523 discloses a lockset mechanism which eliminates the above mentioned frictional engagement between the pawl and the coupler head. The invention of this patent application is directed to the use of a V-shaped camming arrangement on the pawl to cause lifting of the pawl out of engagement with a lug that is carried by the locklifting lever and holds the pawl and lock in lockset position. An important advantage of the invention of this particular patent application is that the lock can be returned to a locked position from lockset by forcing the lug to override the cam on the pawl. It can be appreciated by those skilled in the art that this latter feature cannot be easily obtained without sacrificing a strong, positive interlock of the lug with the cam, when the lock is in a lockset position. The present invention is an improvement of both the inventive concepts outlined above, as well as those found in U.S. Pat. Nos. 2,591,275 and 2,940,610, in that it is designed to eliminate or substantially reduce friction of contact between the pawl and the coupler head or components of the locking mechanism of the coupler, to provide an easier operating locksetting mechanism while providing a better, more positive interlock of the pawl with the locklifting lever, when the lock is in lockset.
Briefly stated, the invention is in a rigid jaw coupler having a spring biased lock, a locklifting lever for moving the lock between locked and lockset positions, and a lockset member or pawl to restrict movement of the locklifting lever and maintain the lock in a lockset position. The locklifting lever is provided with a lug which is designed to interlockingly engage an abutment that is formed in the pawl which is also provided with means for forming, adjacent the end of the pawl extending from the vertically uppermost portion of the coupler head, a fulcrum about which the pawl is caused to rotate as the lock moves from lockset to a locked position. The fulcrumming of the pawl is such that the abutment moves in a direction to cause disengagement from the lug to free the locklifting lever so that the lock can return to a locked position from lockset. The elimination of the frictional engagement between the pawl and coupler head, combined with the rotary feature of the pawl, provides a lockset mechanism which is simpler and easier to operate, while providing a positive interlock of the pawl with the locklifting lever when the lock is in a lockset position.